The timetable may be clear to intelligent and fluent Thai speaking folks but it has me buggered. One could assume that the left hand column (yellow) is the departure time from Surin and the right hand column is the arrival time in Chong Chom although why the early bus takes 75 minutes and the later ones only 60 minutes is strange?
Are there any return schedules?
Bus running times are from 0530 to 1830. Usual running time is 1.5 hours to destination.
I guess you can assume they do a U turn when they get there. So add 1.5 hours onto those times. To get return times.